IV. Knowledge of the Human Being According to Body, Soul or Spirit, Brain and Thinking — The Liver as a Sensory Organ

Now it is the case that when we are awake, these brain cells are then really almost completely dead. And only because the brain cells are dead, can we think. If the brain cells were more alive, we could not think. And one can see that. Because when we are asleep, these brain cells start to come to life a little; especially when we are not thinking, when we are sleeping, the brain cells start to come to life. And the only reason they don't move is because they are so close together, because they can't get out of each other's way. Otherwise, if they started moving, we wouldn't wake up at all.